Voltammetric biosensors for the determination of paracetamol at carbon nanotube modified pyrolytic graphite electrode

The voltammetric oxidation of paracetamol on single-walled carbon nanotubes (SWNT) modified edge plane pyrolytic graphite electrode (EPPGE) was explored in phosphate buffer solution by using square wave voltammetry. Cyclic and square wave voltammetry studies indicated the oxidation of paracetamol at the electrode surface through a two-electron reversible step and fundamentally controlled by adsorption. Besides semi-infinite planar diffusion, the role of thin layer diffusion at nanotube modified electrodes is also suggested. The sensitivity at SWNT modified EPPGE is ∼2 times more than that at MWNT modified EPPGE. Paracetamol gave a sensitive oxidation peak at ∼187 mV at pH 7.2 (μ = 0.5 M) which was used to quantitate the drug in the range of 5-1000 nM with a detection limit of 2.9 × 10^-9 M at SWNT modified EPPGE. The interfering effect of physiologically common interferents on the current response of paracetamol has been reported. The procedure was successfully applied for the assay of paracetamol in pharmaceutical formulations. The applicability of the developed method to determine the drug in human urine samples obtained after 4 h of administration of paracetamol is illustrated.